(1258-1324) Ottomanbey from around 1300-1324, while he was the ruler of his principality from 1293. Osman is often referred to as sultan, but this title was not introduced in the empire until 1394.Osman was the son of Ertugrul, and inherited the position of ruler over a principality with Sögüt as capital. He controlled an effective army, consisting of Muslim warriors called ghazis. While the official purpose of the ghazis were to fight the infidels, they mainly resorted to looting in enemy territory. The main opponent was Byzantium. During Osman's reign, several Byzantine fortresses were conquered, among which Yenisehir.His main campaigns were sieging Nicaea (later, under the Turks renamed to Iznik) and Brusa (later, under the Turks renamed to Bursa). Shortly before his death, he conquered Bursa, which was made into capital of his kingdom.With his death in Sögüt at the age of 66, Osman was succeed by his son, Orhan.